[Dnsmasq-discuss] Problem with TFTP in dnsmasq

Simon Kelley simon at thekelleys.org.uk
Sat Jun 12 17:28:33 UTC 2021

On 08/06/2021 21:54, Brown, Aaron M. wrote:
> Hello all,
> I'm having trouble getting dnsmasq and tftp to work and I'm tearing my hair out. I'm hoping someone can potentially hit me with the clue by four and point out what dumb thing I'm missing.
> In the bigger scope, I'm trying to get PXE booting setup on a server, but at the moment before I even get to anything more complicated, I'm struggling just to get TFTP to work. I have set up my /etc/dnsmasq.conf file as the following:
> interface=bond0
> port=0
> enable-tftp
> tftp-root=/tftp
> log-dhcp
> dhcp-range=<serverIPAddress>,proxy
> dhcp-no-override
> dnsmasq is up and running without errors. I put a simple file in /tftp called "test.txt". The /tftp directory has been set to 755 permissions.
> I then go to client computer and using a tftp client attempt to GET the test.txt file but it times out without retrieving the file.
> There is no firewall running when I do this on either server or client and I can ping from both client and server to each other.
> On the server, I see in a tcpdump of port 69 that the client is making RRQ requests. When I look at the status of the dnsmasq service I see:
> Jun 08 16:13:46 <serverName> dnsmasq-tftp[258381]: failed sending /tftp/test.txt to <clientIPAddress>
> There's a similar message in /var/log/syslog as well for dnsmasq-tftp failing to send the file. I've been pouring over the docs/man pages and the sample .conf file, but I'm clearly not understanding what I'm missing.
> Anyone have any ideas? I've searched the web for similar problems, but I haven't been able to find anything that resembles my situation. Usually people seem to have issues after this point with what TFTP is passing out, not just getting TFPT up and running.

Dnsmasq is timing out awaiting acknowledgement from the client. Tftp
transactions start with a packet from the client to port 69, and the
reply is from a different, newly allocated port. The client should then
use that port for subsequent requests, so  it's worth looking at all UDP
traffic in tcpdump.

What version of dnsmasq are you using?


> Server OS: Ubuntu 20.04 Server
> Client OS: Ubuntu 20.04 Desktop
> Aaron M Brown
> Engineering College Computing
> Desktop Administrator
> NI1013A - 419.530.8022
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